Granville eastwood bradshaw



G. E. BRADSHAW.

CARBURETER.

APPLICATION FILED. Emu, 19m.

1 ,339,095, Patented May 4, 1920.

C) O K F 1 I J L GRANVILLE EASTWOOD BRADSHAW, 0F 'WALTON-ON-THAMES, ENGLAND.

cARBURErnR.

Specification of Letters Patent.

Patented- May 4, 1920.

Application filed February 12, 1918. Serial No. 216,813.

Z all whom it may concern:

Be it known that I, GRANVILLE Eesrwoon BILUMHAXl, a subject of the King of Great llrituiu, residing at A. B. G. Motor lVorks, llersham, lValton-onl hames, in the county of Surrey, England, have invented new and useful Improvements in Carburetors for Internal-Combustion Engines, of which the following is a specification.

carburetors for explosion motors, and consists elf a device for automatically preventing an, excess of fuel (petrol) being delivered by a jet, as the speed of the motor increases. In the present invention, secondary tube, which is situated in the path of the air which passes through the primary tube.

This secondary tube is smaller than the primary tube, and the jet, which conveys the petrol from a constant-level chamber (of known practice) is situated in this secondary tube. It has been found in. practice that with this arrangement the fuel to air ratio remains sensibly constant over a large range from low to high speeds.

l throttle is inserted between the jet and the nurtor, and a slow running tube is attached to the secondary tube. The slow run ning tube is extended to a position close to the th rottle, so that when the throttle is only slightly open, the suction becomes more conentrulcd on the secondary tube, in order to maintain the requisite flow of fuel when the engine is running slowly, such concentration being in relative inverse proportion to the throtl in opening, i. 0. decreased as the throtlie is opened.

The petrol. jet which is inserted in the secondary tube, may be below the maintained level o l the petrol, so as to form a small well of petrol above the ct, for any purposes that may be desired.

The primary or secondary tube may be bell-nuuithed, or of any other convenient shape necessary to give the correct propor tion of air and fuel.

The accompanying drawings illustrate one form of the inventioinbeing a longitudinal section through a carbureter made in accordance therewith.

An object of the invention is to provide a carbmeter having novel structural features and arrangel'l'ients which willprove efficient and satisfactory in use.

With the foregoing and other objects in .lhis invention relates to improvements in view, the invention consists in the details of construction, and in the arrangement and combinaton of parts to be hereinafter more fully set forth and claimed.

In describing the invention in detail, refrence will be had to the accompanying drawings forming part of this specification, in which the invention is illustrated by a view in vertical section.

The ordinary well-known features are indicated, such as the float chamber A, body of earbureter B, choke tube C, which is the primary tube referred to above, and throttle barrel D, with throttle spindle E. i use a The choke tube C has a relatively wide area above the choke portion in which the air can expand slightly; the suction in the larger portion of the tube being of course under the influence of the action of the pistons in the cylinders.

Inner choke tube F is fitted inside the body B. The jet G delivers into this secondary tube F, and is set at an angle of 45 thereto or may be set at any angle. Opposite to the point of delivery of the jet G, another. small tube H, or tubular extension,

called a slow-running tube, is led from the inner secondary tube F to a point near the throttle. A needle I is inclosed Within the tube H, but preferably without touching the walls thereof, such needle, in combination with the tube H, enables the latter to retain the fuel which is injected into it when the carbureter is temporarily flooded with petrol, such retention being due to the capillary eifect of the surfaces of the needle and tube combined. The needle I nay also be extended in the form of a tapered extremity at its lower end for regulating the amount of opening of the jet G, its upper end being screw-threaded to work in a correspondingly threaded boss J on the carbureter and carrying a knurled head K for primary adjustment, and an adjustable lever L, if desired, for use upon aircraft, the needle being serviceable as an altitude corrector, for the purpose of adjusting the flow of fuel to suit the altitude at which the motor is working.

The knurled nut can be employed for turning the needle I whose threads engage threads of the casing so that by loosening the lever L in turning the knurled nut, the valve canbe caused to travel in or out of the orifice in which it is located and as the inner end of the valve is tapered, the orifice is restricted or unguarded according to the direction of rotation of the needle valve. It is the purpose of the inventor to secure an adjustment approximating the one desired and then when the lever is secured to the needle valve, it will control the position of the needle valve and open and close the jet while the motor is being run.

A movement limited by the angular travel of lever L, is then given to the jet control, covering any desired range between a very weak and a very rich mixture, and it should be noted that this carbureter is entirely automatic, in that this control need not be varied with various throttle openings and en ine speeds.

f the jet lever L, for instance, is set for a weak mixture, as marked upon a fixed name plate or the like, the mixture is weak in all throttle positions, and at all engine speeds. Similarly if the lever is set for a rich mixture, the mixture is rich in all. throttle positions, and at all engine speeds. The rich position will be that in which the needle 1 is withdrawn farthest and vice versa.

If the jet control, for instance, is set for a weak mixture, the mixture is weak at all throttle positions and at all engine speeds. Similarly, if the control is set for a rich mixture, the mixture is rich at all throttle positions and at all engine speeds, and these positions are determined by the size of the openings produced for the passage of the fuel.

This control needle. I greatly facilitates starting from cold, due to the increased capillary attraction of the tube so fitted.

The mixing of the petrol and air is obtained by the velocity of the rich mixture issuing from the inner secondary tube F and by the air velocity outside the inner choke tube.

The float chamber A may be of the standard pattern, but is shown in the drawing as being in operative relation to the side oi the jet boss M. The jet boss M with jet (i being set, as stated, at an angle of approximately, the carbureter can in this form be used as a horizontal or vertical one at will, and the fuel level in the jet remains the same in either position.

The present UZIIlJLlIQtQI has in etfect only one variable, and this is variable without leaving the driving seat. It is also of substantial design, and having no intricate parts, it is not liable to accidental damage.

The control of the jet by the needle I permits the use of different qualities of fuel. without re-setting the carbureter, and initial adjustment for slow running is obtained by the choice of the correct size of slow-running tube ll.

I claim.

1. In a carbureter, a float chamber, a body portion including a relatively large tube, a jet providing communication between the relatively large tube and float chamber, a secondary tube disposed intermediate the length of the relatively large tube, and sup ported by the jet and having communication therewith, a relatively small tube having communication with the secondary tube and having one of its ends lying in parallel relation with one of the side walls of the relatively large tube, and a needle valve for controlling the passage of fuel from the jet.

2 In a carbureter, a body portion including a relatively large tube, a choke tube forming a part of the relatively large tube, a jet extending into the relatively large tube at one angle with relation to the side walls thereof, a secondary tube having a wide lower end and a relatively narrow upper end, said jet discharging into the secondary tube, a relatively small tube having communication with the secondary tube and having one of its ends extending upwardly, and a needle valve for controlling the passage of fuel from the ct into the secondary tube and relatively small tube.

GRANVILLE EASTWOOD BRADSHAW.

\Yitnesses:

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